Combining multicore imaging fiber with matrix addressable blue/green LED arrays for spatiotemporal photonic excitation at cellular level

We have developed a microscale flexible optical image projection device, integrating a matrix addressable blue/green 2-D LED array to a multicore imaging fiber. The scalable matrix addressable LED design was to enable electrical access to individual elements in the densely packed 2-D LED array. A prototype 10 x 10 element array was fabricated by specific device process sequence, using deep reactive ion etching and polyimide etch-back processes for device isolation and planarization. Individual elements of the array have been operated under continuous-wave current injection up to a few kiloamperes per square centimeter suggesting uncompromised performance and robustness of the planarized device structure. The device was butt-coupled to a 30 000 pixel multicore image fiber to generate a spatiotemporal pattern of light at the output end of the fiber. As application demonstrations, selected spatiotemporal patterns of illumination have been projected either to the eye of Xenopus laevis tadpoles in studies of their developing visual system, or directly to excitable neural cells in the brain.